The U.S. Department of Health and Human Services, National Institutes of Health, National Cancer Institute (NCI), Division of Cancer Control and Population Sciences (DCCPS), Surveillance Research Program (SRP) requires annual population estimates for counties and census tracts based on the counts produced by the US Census Bureau. The primary functions of the NCI/DCCPS/SRP are to : (1) plan, develop, coordinate, and maintain a comprehensive national program to measure and report periodically on cancer in the United States population, providing accurate, reliable, and detailed national estimates of cancer incidence, survival and mortality and integrates patient data with associated demographic, behavioral and medical data; (2) plan, develop and direct a quality control program which establishes, monitors, and maintains national and international collaboration and liaison with organizations and agencies that promote comparability of cancer information systems; (3) plan and direct surveillance studies that coordinate with other research efforts in the Division, Institute and other Federal agencies; and (4) develop and implement, using statistical modeling and operations research techniques, methodologies to resolve quantitative questions in cancer prevention, control, and surveillance, including analysis of trends, forecasting cancer rates, and development of models for diffusion of cancer control interventions.